This renewal application proposes extensive studies focusing on the molecular genetics of the cutaneous basement membrane zone (BMZ) towards delineating the molecular defects in various forms of epidermolysis bullosa (EB). The proposed studies are designed to test the hypothesis that genes for structural macromolecules expressed at the BMZ cause one or more forms of EB. This application is based on solid progress during the past four years of research. The highlights of this progress include: (a) cloning of BMZ genes encoding human type VII collagen, bullous pemphigoid antigens 1 and 2, nidogen, and laminin A, B1 and B2 chain sequences; (b) chromosomal localization of 5 previously unassigned BMZ genes within the human genome; (c) demonstration of genetic linkage between the type VII collagen gene locus (COL7AI) and dominant dystrophic EB mutations in 4 families with defective anchoring fibrils; (d) genetic linkage of a family with dominant simplex EB to a locus on chromosome 12q adjacent to the type II keratin gene cluster, and mapping of another EB simplex family to a locus on chromosome 1q. The proposal for continuation of these studies entails concentrated, multi-disciplinary studies to be performed by investigators participating in the collaborative research within the Jefferson Institute of Molecular Medicine. The five component projects are highly interdependent. Project 1, "Genetic Linkage Analysis of EB", is vital to rule in or rule out specific genes and alleles as candidates for mutation in families with EB. Project 2, "Genetic Defects in BMZ Molecules", will provide precise information on the specific mutations in the gene-protein systems that are at fault in various forms of EB. Project 3, " Transgenic Mice with EB", will introduce mutated BMZ gene sequences, which have been identified in Project 2, into transgenic mice, to examine the consequences of such mutations. Project 4, "Biology of Type VII Collagen", will concentrate on elucidation of various aspects of cellular and molecular biology of type VII collagen towards identification of critical protein structures and elements regulating the expression of this gene. Project 5, "Protein and Gene Structure for BMZ Components", will provide additional gene probes and information about the normal gene structures that are essential for studies in Projects 1, 2 and 3. These multidisciplinary studies are expected to provide precise information on the underlying molecular defects in various forms of EB. Such information is of critical importance in developing a definitive classification, for development of prenatal diagnostic tests, and to provide a basis for devising novel therapeutic approaches for this disease.